This study provides data on post-hospitalization medication treatment trends for unstable angina between 1990 and 1995. We conducted an observational cohort study at the Veterans Affairs Puget Sound Health Care System (VAPSHCS). Computerized records of hospital discharges and cardiac catheterizations were used to identify unstable angina diagnoses among veterans between 1990 and 1995. Discharge medications issued within 90 days after discharge were ascertained from computerized outpatient pharmacy records. Of the 1,100 veterans discharged with unstable angina, 885 (80%) filled a prescription through the VAPSHCS within 90 days after discharge. Neither use of aspirin nor use of beta blockers increased between 1990 and 1995: overall use averaged 76% for aspirin (78% of those without potential contraindications) and 32% for beta blockers (36% of those without potential contraindications). Use of non-dihydropyridine calcium antagonists--primarily diltiazem--decreased from 57% to 40% (p <0.01), whereas use of dihydropyridine calcium antagonists increased from 12% to 26% (p <0.01). Thus, pharmacy records indicated that aspirin use was high although it was lower than expected, possibly due to ready availability outside the VAPSHCS pharmacy. The low frequency of beta-blocker use and the increasing reliance on dihydropyridine calcium antagonists through 1995 to treat unstable angina may be an opportunity to improve veteran care according to Agency for Health Care Policy Research recommendations.